Helicopter-borne magnetic gradiometry for mineral exploration: Effects of system movement in flight

Publication

Publication

A coherent oscillating noise on the scale of ~0.1 nT, in the 0.27-0.30 Hz frequency range, has been detected in helicopter-borne triaxial magnetic gradiometric data when the system flies over low signal areas. Research has been completed to carefully characterize this noise, identify its source, and to devise correction strategies to improve sensitivity and accuracy of the measured gradients. Translational movements were dismissed as a significant contributing factor as they oscillate at a much lower frequency than the observed noise. Rotational movements have the same frequency of the oscillating noise but its most likely cause is a mechanical source, related to system design. Mathematical removal of the oscillating noise by derotation was unsuccessful but notch filters proved an effective method. Future investigation into other solutions, such as altering the mounting system or watching bird movement with a camera, could be undertaken.